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Finding the Fourth Proportional to 421.60, 632.40 and 405.40

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Solution

The fourth proportional to 421.60, 632.40 and 405.40 is: 608.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    421.60 : 632.40 = 405.40 : x
  2. Step 2: Convert to fraction form
    421.60/632.40 = 405.40/x
  3. Step 3: Cross multiply
    421.60x = 632.40 × 405.40
  4. Step 4: Simplify right side
    421.60x = 256,374.96
  5. Step 5: Solve for x
    x = 256,374.96/421.60
  6. Step 6: Final answer
    x = 608.10

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Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.